The invention relates to gate valves.
The invention provides a gate valve comprising a wedge shaped gate movable into a passageway to seal the passageway, the wedge shaped gate having first and second sides and a butt region, the first and second sides converging towards the butt region, the first side having a perimeter seal facing upstream, the second side having a perimeter seal facing downstream, each perimeter seal merging into a butt end seal for sealing against a face of the passageway opposed to the butt end, there thus being two butt seals spaced apart with respect to the axis of the passageway, the wedge shaped gate having a concavity within each perimeter seal to reduce the weight of the gate, the seals being coated with resilient material and the geometry of the valve being such that although the butt end seals undergo a substantially greater degree of compression than the perimeter seals, for a given movement of the gate, the final degree of compression of all the seals, when the valve is finally closed, is-substantially similar.
There may be a bore through the gate, perpendicular to the axis of the passageway, to accommodate a spindle for operating the valve, the bore having an exit hole in the butt end of the gate, positioned between the spaced apart butt end seals.